Originally Posted by
FlightDetent
It's inertia, INTBH. Those 20k+ pilots must have flown commercially, i.e. heavier planes, where the effect can be seen. Although like you say the craft is moving within a practically uniform parcel of air, Newton's laws still apply. The inertial system is the spheres, so the physics is there.
I have no claim how pronounced or measurable the effect is on those beauties with low wing loading, but our aircraft do show. Level flight, fixed thrust, steady heading with 90° cross-wind: there is a difference in which way you'd turn.
Lets start with basics. Assume a 100 kt airplane flying east in still air with 100 kt groundspeed (obviously). The airplane turns to a west heading. groundspeed is now 100 kt West
What is the velocity change from the east heading to the west heading?
Now, same airplane flying East in a 50 kt wind out of the East (direct headwind) at 50 kt GS. The airplane turns to a west heading. Groundspeed is now 150 kts.
What is the velocity change in this example?